The messermeister angle guide is a great way to train yourself in developing the ability to consistently sharpen a knife at the same amount of degrees. Depending on the width of the blade, the guide will allow you to initiate the stroke at approximately 15-20 degrees. It can be used on a flat water/oil stone or a honing/sharpening steel of any type. After practicing with the device, one will eventually develop the ability to free hand the stroke with amazing accuracy.